A newly isolated strain of Serratia sp. from an oil spillage site of Assam shows excellent bioremediation potential

Next-generation nanotechnology-integrated biosurfactants: Innovations in biopesticide development for sustainable and modern agriculture

The increasing global demand for eco-friendly agricultural practices necessitates the development of innovative pest management solutions, effectively addressing the environmental and ecological issues associated with traditional chemical pesticides, such as pest resistance, environmental contamination, and non-target organism toxicity. Biosurfactants, biologically derived amphiphilic molecules from microbial and plant sources, offer distinct advantages including biodegradability, excellent surface-active properties, and inherent antimicrobial efficacy, making them as promising candidates for sustainable pest management and control. Concurrently, nanotechnology introduces innovative delivery mechanisms, enhancing biopesticide stability, solubility, and targeted application, significantly minimizing off-target impact and environmental footprint. This review emphasizes recent breakthroughs in integrating biosurfactants with nanotechnological strategies to produce advanced biopesticides. Key advancements include the role of biosurfactants to increase the bioavailability and effectiveness of active ingredients and utilizing nanopesticides for targeted pest control with improved precision. Combining the unique amphiphilic properties of biosurfactants and the precise targeting capabilities of nanocarriers presents substantial improvements in pest management efficacy and aligns closely with Integrated Pest Management (IPM) principles. Despite these promising developments, significant knowledge gaps remain, including understanding the interactions between biosurfactants, nanomaterials, and the environmental matrices, as well as assessing long-term ecological impacts and safety profiles associated with nanopesticide usage. This article outlines critical research areas requiring further exploration to optimize biosurfactant-nanotechnology systems for large-scale agricultural deployment. Addressing these challenges will facilitate broader adoption, ensuring sustainable pest control practices that significantly contribute to global food security and environmental preservation. Integrating biosurfactants with nanotechnology represents a transformative approach in agricultural pest management, offering substantial potential to revolutionize sustainable agriculture through effective, environment-friendly solutions.

Microbial biosurfactants: Green alternatives and sustainable solution for augmenting pesticide remediation and management of organic waste

Pesticide pollution remains a significant environmental challenge, necessitating the exploration of sustainable alternatives. Biosurfactants are a class of unconventional surface-active chemicals that are produced by microorganisms. Biosurfactants have many applications in treating oil spills, emulsifiers, pharmaceuticals, and agriculture. Compared to chemical surfactants, they have benefits such as biodegradability, less toxicity, and a greener option because they are derived from microbes. Biosurfactants have recently been shown to have the potential to speed up pesticide cleanup. Biosurfactants are used in pesticide remediation because of their exceptional foaming ability, high selectivity, and wide range of pH, salinity, and temperature operating windows. Microbial biosurfactants emerged as potential agents for the treatment of organic waste and agricultural residue. This review unfolds the promising realm of microbial biosurfactants as green solutions for environmental sustainability, particularly in agricultural practices, with special reference to pesticide remediation. This article highlights the escalating need for eco-friendly alternatives, paving the way for discussing biosurfactants. Moreover, the articles discuss in detail various advancements in the field of rapid screening of biosurfactants, either using a conventional approach or via advanced instruments such as GC-MS, HPLC, NMR, FTIR, etc. Furthermore, the article unveils the molecular mechanisms and the microbial genes driving biosurfactant synthesis, offering insights into enhancing production efficiency. Moreover, the article explores diverse applications of microbial biosurfactants in sustainable agriculture, ranging from soil remediation to crop protection. The article also highlights the various functions of microbial biosurfactants for enhancing the decomposition and recycling of organic waste and agricultural residues, emphasizing their potential for sustainable waste management strategies. Overall, the review underscores the pivotal role of microbial biosurfactants as green alternatives for addressing pesticide pollution and advancing environmental sustainability.

Soil contamination by diesel fuel destabilizes the soil microbial pools: Insights from permafrost soil incubations

Arctic contamination by diesel fuel (DF) is of great concern because of the uncertain feedback of permafrost carbon (C) and soil microbiota to DF in the context of climate change in high latitudes. We conducted a laboratory incubation experiment with a gradient of DF addition ratios to examine the responses of the soil microbiota of the typical permafrost soils in the tundra ecosystems of the Norilsk region (Siberia). The study revealed initial heterogeneity in the microbial activity of the studied soils (Histic Gleyic Cryosols (CR-hi,gl), Turbic Cryosols (CR-tu), Turbic Spodic Folic Cryosols (CR-tu,sd,fo), Gleyic Fluvisols (FL-gl)). We applied the two-pool model for evaluation of the effect of DF on the proportions of C pools and revealed significant differences between soil types in the fast and slow C pools in response to DF addition. The results showed that DF addition treatments had varying effects on the fast and slow C pools, microbial activity, and microbial community structure in the studied soils. For minor exceptions, DF dramatically accelerated C loss from the slow C pool in all soil types. We assume that differences in C pool and microbiota responses to DF addition were caused by soil texture and changes in microbial community structure. We isolated Serratia proteamaculans, S. liquefaciens, S. plymuthica, Rhodococcus erythropolis, Pseudomonas antarctica, P. libanensis, P. brassicacearum, and P. chlororaphis from the DF-polluted soils. These species are recommended for bioremediation to mitigate the DF contamination of permafrost soils, especially regarding climate change and the sustainable well-being of Arctic ecosystems.

Microbial biosurfactants: a review of recent environmental applications

Microbial biosurfactants are low-molecular-weight surface-active compounds of high industrial interest owing to their chemical properties and stability under several environmental conditions. The chemistry of a biosurfactant and its production cost are defined by the selection of the producer microorganism, type of substrate, and purification strategy. Recently, biosurfactants have been applied to solve or contribute to solving some environmental problems, with this being their main field of application. The most referenced studies are based on the bioremediation of contaminated soils with recalcitrant pollutants, such as hydrocarbons or heavy metals. In the case of heavy metals, biosurfactants function as chelating agents owing to their binding capacity. However, the mechanism by which biosurfactants typically act in an environmental field is focused on their ability to reduce the surface tension, thus facilitating the emulsification and solubilization of certain pollutants (in-situ biostimulation and/or bioaugmentation). Moreover, despite the low toxicity of biosurfactants, they can also act as biocidal agents at certain doses, mainly at higher concentrations than their critical micellar concentration. More recently, biosurfactant production using alternative substrates, such as several types of organic waste and solid-state fermentation, has increased its applicability and research interest in a circular economy context. In this review, the most recent research publications on the use of biosurfactants in environmental applications as an alternative to conventional chemical surfactants are summarized and analyzed. Novel strategies using biosurfactants as agricultural and biocidal agents are also presented in this paper.

Bioremediation of motor oil-contaminated soil and water by a novel indigenous Pseudomonas otitidis strain DU13 and characterization of its biosurfactant

Production of biosurfactant by a novel indigenous isolate Pseudomonas otitidis strain DU13 and its role in bioremediation of petroleum hydrocarbon is reported. The identity of the isolate was confirmed by 16S rDNA gene sequencing analysis (Genbank accession: MK177190). The biosurfactant produced by the isolate could reduce the surface tension of petroleum supplemented medium by 46% just after 7 days of treatment. The emulsification index (E ₂₄ ) of the surfactant was found 37, 35, and 20%, respectively, against used motor oil, diesel, and kerosene. The FTIR spectrum of the crude biosurfactant showed the presence of υ_C-H stretch, υ_CH2, υ_-C=C stretch and υ_C-H bonding. The isolated strain could degrade 26% of TPH content of used motor oil in liquid culture. Whereas, ex situ pilot-scale field trial demonstrated very high bioremediation potential of the isolate in terms of germination rate of Vigna radiata and Cicer arietinum seeds and plant growth just after 20 days of treatment.

Diversity and Oil Degradation Potential of Culturable Microbes Isolated from Chronically Contaminated Soils in Trinidad

Trinidad and Tobago is the largest producer of oil and natural gas in Central America and the Caribbean. Natural crude oil seeps, in addition to leaking petroleum pipelines, have resulted in chronic contamination of the surrounding terrestrial environments since the time of petroleum discovery, production, and refinement in Trinidad. In this study, we isolated microbes from soils chronically contaminated with crude oil using a culture-dependent approach with enrichment. The sampling of eight such sites located in the southern peninsula of Trinidad revealed a diverse microbial composition and novel oil-degrading filamentous fungi and yeast as single-isolate degraders and naturally occurring consortia, with specific bacterial species not previously reported in the literature. Multiple sequence comparisons and phylogenetic analyses confirmed the identity of the top degraders. The filamentous fungal community based on culturable species was dominated by Ascomycota, and the recovered yeast isolates were affiliated with Basidiomycota (65.23%) and Ascomycota (34.78%) phyla. Enhanced biodegradation of petroleum hydrocarbons is maintained by biocatalysts such as lipases. Five out of seven species demonstrated extracellular lipase activity in vitro. Our findings could provide new insights into microbial resources from chronically contaminated terrestrial environments, and this information will be beneficial to the bioremediation of petroleum contamination and other industrial applications.

Growth kinetics of Pseudomonas aeruginosa RS1 on fluorene and dibenzothiophene, concomitant degradation kinetics and uptake mechanism

The current study illustrates the growth kinetics of an efficient PAH and heterocyclic PAH degrading bacterial strain, Pseudomonas aeruginosa RS1 on fluorene (FLU) and dibenzothiophene (DBT) over the concentration 25-500 mg L-1 and their concomitant degradation kinetics. The specific growth rate (µ) was found to lie within the range of 0.32-0.57 day-1 for FLU and 0.24-0.45 day-1 for DBT. The specific substrate utilization rate (q) of FLU and DBT over the log growth phase was between 0.01 and 0.14 mg FLU mg VSS-1 day-1 for FLU and between 0.01 and 0.18 mg DBT mg VSS-1 day-1 for DBT, respectively. The µ and q values varied within a narrow range for both FLU and DBT and they did not follow any specific trend. Dissolution together with direct interfacial uptake was the possible uptake mechanism for both FLU and DBT. The q values over the log growth phase depicts the specific substrate transformation rates. Kirby-Bauer disc diffusion studies performed using an E. coli strain indicated accumulation of some toxic intermediates of FLU and DBT during their degradation. Decrease in TOC and toxicity towards the end of the degradation experiments indicates further utilization of the intermediates.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s13205-021-02742-7.

Characterisation of hydrocarbon degradation, biosurfactant production, and biofilm formation in Serratia sp. Tan611: a new strain isolated from industrially contaminated environment in Algeria

A novel bacterial strain was isolated from industrially contaminated waste water. In the presence of crude oil, this strain was shown to reduce the rate of total petroleum hydrocarbons (TPH) up to 97.10% in 24 h. This bacterium was subsequently identified by 16S rRNA gene sequence analysis and affiliated to the Serratia genus by the RDP classifier. Its genome was sequenced and annotated, and genes coding for catechol 1,2 dioxygenase and naphthalene 1,2-dioxygenase system involved in aromatic hydrocarbon catabolism, and LadA-type monooxygenases involved in alkane degradation, were identified. Gas Chromatography-Mass Spectrometry (GC-MS) analysis of crude oil after biological treatment showed that Serratia sp. Tan611 strain was able to degrade n-alkanes (from C₁₃ to C₂₅). This bacterium was also shown to produce a biosurfactant, the emulsification index (E24) reaching 43.47% and 65.22%, against vegetable and crude oil, respectively. Finally, the formation of a biofilm was increased in the presence of crude oil. These observations make Serratia sp. Tan611 a good candidate for hydrocarbon bioremediation.

Isolation and characterization of biosurfactant-producing Serratia marcescens ZCF25 from oil sludge and application to bioremediation

A biosurfactant (BS) is a surface-active metabolite that is secreted by microbial metabolism, and can be used as a substitute for chemically synthesized surfactants. The first and most critical step to the successful application of BSs is to isolate bacterial strains with strong BS-producing capabilities. In this study, a BS-producing Serratia marcescens ZCF25 was isolated from the sludge of an oil tanker. Through polyphasic characterization using Fourier-transform infrared spectroscopy, thin layer chromatography, and gas chromatography-mass spectrometry, the produced BS was classified as a lipopeptide; it can decrease the water surface tension from 72.0 to 29.50 mN m^-1 and has a critical micelle concentration of 220 mg/L. The BS showed a high tolerance over a wide range of pH (2-12), temperature (50-100 °C), and salinity (10-100 g/L). Furthermore, the inoculation of S. marcescens ZCF25 with fracturing flowback fluids could significantly (P < 0.05) reduce the chemical oxygen demand, concentration of alkanes, and concentration of polycyclic aromatic hydrocarbons, with removal efficiencies of 48.9%, 65.57%, and 64%, respectively. This is the first study on the application of BS-producing S. marcescens to treat fracturing flowback fluids. S. marcescens ZCF25 is a promising candidate for use in various industrial and bioremediation applications. Graphical abstract.